Conventionally, it is known that useful information relating to a health condition of a person is obtained from odor of the breath or urine of the person.
Research and development for detecting the breath of a person using a gas sensor and finding a disease at an initial stage at which the person does not have a subjective symptom are being proceeded.
For example, a method is examined in which presence or absence of a disease or affection is decided by taking focusing on a specific chemical material in the breath and detecting the specific chemical material using a gas sensor.
Especially, if a gas sensor capable of detecting aldehyde with a high sensitivity and besides capable of distinguishing aldehyde from the other substances with a high selection ratio can be implemented, then the gas sensor can be used, for example, for checking of lung cancer or the like.
It is to be noted that, as a sensor for monitoring the concentration of a volatile organic compound in a room, a gas sensor has been proposed which uses a conductive organic-inorganic hybrid material in which organic macromolecules containing, as a main component, poly-naphthylamine, poly amino anthracene or a derivative of the substances are inserted between layers of an inorganic compound containing molybdenum oxide as a main component and which is capable of detecting acetaldehyde preferentially to formaldehyde. Further, as a gas sensor for detecting the freshness of vegetables or the like, also a gas sensor has been proposed which uses a metal oxide such as tin oxide and is capable of detecting aldehydes.